FirebaseVisionText.Element

Roughly equivalent to a space-separated "word" in most Latin languages, or a character in
others. For instance, if a word is split between two lines by a hyphen, each part is encoded
as a separate Element.

Gets the four corner points in clockwise direction starting with top-left. Due to
the possible perspective distortions, this is not necessarily a rectangle. Parts of the
region could be outside of the image.